Low loss high-frequency transmission line



Jan. 12, 1954 K. WILDBERG LOW LOSS HIGH-FREQUENCY TRANSMISSION LINEFiled April 19, 1950 INVENTOR. Lzsua .K.Wu DsERe ATTORNEY Patented Jan.12, 1954 LOW LOSS HIGH-FREQUENCY TRANSMISSION LINE Leslie K. Wildberg,Shaker Heights, Ohio, as-

signor to Radix Wire Company, Cleveland, Ohio, a corporation of OhioApplication April 19, 1950, Serial No. 156,873

1 Claim.

This invention relates, as indicated, to transmission lines, but hasreference more particularly to low loss, high frequency transmissionlines.

These lines, which are commonly used to connect television antennae totelevision sets, and for other high frequency purposes, such asfrequency modulation, usually include two or more parallel conductorwires embedded in a dielectric material, the electrical characteristicsof the line being determined by the spacing between the wires, the sizeof the wires, and the dielectric constant of the material in which thewire is embedded.

For ordinary television purposes, various lines having a range ofnominal impedance from '72 to 300 ohms are most frequently used. In onetype of such line, the conductors or wires are embedded in the marginalportions of a fiat ribbon or band of plastic material, so that strippingor detachment of the conductors from the band, for attachment toterminals or contacts, requires the use of special tools, and involvesconsiderable difficulty and the expenditure of a great deal of workingtime. Moreover, the large, unbroken, flat area between the conductors ofthe line is conducive to the accumulation of drops of water on the line,which cause variations in the impedance of the line, and isobjectionable from other standpoints.

The present invention has as its primary object the provision of a novellow loss, high frequency transmission line, embodying conductor wireswhich are easily and quickly separable from the line for strippingpurposes, without the necessity of using special tools.

Another object of the invention is to provide a transmission line of thecharacter described, which is so constructed as to prevent accumulationof drops of water on the line, and is therefore characterized by aconstant impedance at all points along the line.

A further object of the invention is to provide a transmission line ofthe character described, which can be manufactured in large quantitiesat a fairly low cost, competitive with existing types of transmissionlines.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings, forming a part of this specification, andin which like numerals are employed to designate like parts throughoutthe same,

Fig. 1 is a plan view, on an enlarged scale, of

a fragment or length of transmission line, embodying the novel featuresof the invention, and

Fig. 2 is a cross-sectional view, taken on the line 22 of Fig. 1.

Referring more particularly to the drawings, reference numeral Idesignates a fiat band or ribbon of a plastic, dielectric material, ofappreciable thickness, having conductor wires 2 and 3 embedded in themarginal portions of the band and extending longitudinally of the band.The marginal portions of the band in which these conductor wires areembedded, and which are designated by reference character 4, aredemarcated from the body of the band by lines 5,. which may be made byroller cutters having knife-like edges, or may be molded into thedielectric plastic material. These lines, which reduce the thickness ofthe band along the lines, greatly facilitate separation of the marginalportions 4 from the band by simply tearing the latter from the band, asby hand. The plastic covering may then be easily stripped from theportions 4 by any conventional means, to expose the wires 2 and 3, asfor connection of the latter to terminals or contacts.

The facility with which the portions 4 of the band can be stripped fromthe body of the band, avoids the use of tools, and considerably reducesthe time required for stripping purposes.

The fiat areas between the portions 4 of the band are broken up orinterrupted by ribs 6 extending longitudinally of the band,approximately midway between the portions 4 of the band and parallelwith the latter. These ribs, which are molded integrally with the band,preferably have relatively sharp ridges or upper edges 1. These ribsfunction to deflect or split drops which would otherwise accumulate onthe flat areas, causing the drops to roll or fall off the line, and thusprevent accumulation of water on the line. In this way, the ribs do awaywith variations in the impedance of the line, providing a line ofrelatively constant impedance at all points along the line.

It is to be understood that the form of my invention, herewith shown anddescribed, is to be taken as a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may beresorted to, without departing from the spirit of my invention or thescope of the subjoined claim.

Having thus described my invention, I claim:

A low loss, high frequency, transmission line comprising a band orribbon of dielectric material having portions of substantially circularcross-section at the margins thereof, said portions having conductorWires embedded therein, said band having a central portion extendingbetween said marginal portions of a width considerably larger than thediameter of said marginal portions and of a thickness less than thediameter of said marginal portions, and ribs extending from bothsurfaces and formed integrally with said central portion, said ribsdisposed substantially midway between said marginal portions andextending substantially parallel with the latter, said ribs havingrelatively sharp ridges lying in the plane of the outer surfaces of saidcircular marginal portions, said marginal portions being separated fromsaid central portion by lines of demarcation which reduce the thicknessof the central portion of the band, so as to facilitate tearing orstripping of said marginal portions from the band.

LESLIE K. WILDBERG.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 605,256 Mershon June 7, 1898 1,533,936 Martin-Harvey Apr. 14,1925 1,965,953 Curtis July 10, 1934 2,158,867 Schwabacher May 16, 19392,204,782 Wermine June 18, 1940 2,232,085 Troche Feb. 18, 1941 2,361,374Abbott Oct. 31, 1944 2,628,998 Frisbie Feb. 17, 1953 FOREIGN PATENTSNumber Country Date 477,019 Great Britain Mar. 11, 1936 555,228 GreatBritain Aug. 11, 1943 20 p. 125; received in Patent Ofiice, Oct. 15,1946.

(Copy in Div. 65.)

